Malaria, an infectious disease widespread in tropical and subtropical regions, is caused by infection with the parasitic protist Plasmodium. While there are four species of Plasmodium that can infect humans, the species Plasmodium falciparum causes the most dangerous form of malaria with the highest mortality rate. According to the World Health Organization (WHO), there are over 200 million confirmed malaria cases annually, resulting in nearly one million deaths.
In addition, malaria has a negative impact on the wealth of nations and individuals. According to the World Bank, malaria costs Africa about US$12 billion per year and slows gross domestic product (GDP) by over 1% each year. The burden of malaria traps families and communities into deeper poverty by lost productivity and the negative impact on domestic and foreign investment and tourism. Furthermore, malaria greatly affects the structure of society as high mortality rates often afflict the age group under five years old.
The Centers for Disease Control and Prevention in USA notes that although complete elimination of the malaria parasite would be optimal, this is not realistic for most countries endemic for malaria. Improved management of malaria cases is fundamental to control the spreading of malaria.
Rapid diagnostic tests (RDT) are critical for the management of malaria to reduce the morbidity, mortality and transmission of malaria. Commonly-used RTDs for malaria include microscopic, polymerase chain reaction (PCR), and antibody based assays. Microscopic diagnosis of malaria, which is based on the microscopic observation of the malaria parasite in a blood smear, can differentiate various species of Plasmodium. PCR based assays can also distinguish various species of Plasmodium with high sensitivity. However, both the microscopic and PCR-based diagnostic tests require expensive equipment and highly trained healthcare workers that are generally not available to the majority of the at-risk population in developing countries.
Antibody based assays utilize antibodies for detection of Plasmodium antigens. The commonly-used Plasmodium antigens for malaria diagnosis include plasmodium lactate dehydrogenase (pLDH), histidine rich protein 2 (PfHRP2), and aldolase. While antibody-based rapid diagnostic assays have greatly benefited malaria management, they suffer from significant shortcomings including thermal instability, batch to batch variations, and high cost of production.
Therefore, there is a need for improved methods for malaria diagnosis.